https://www.febo.com/pipermail/time-nuts/2017-March/104374.html
The cesium oven acts as an evaporator for liquid cesium which melts at 28.5° C. One of our beam tubes has 83°C for its operating temperature. It also calls for a A11R11 and A11R12 of 3.83 K and 42.2K which is 3.51K. Oven power is specified at 2.2V and 0.9A or 1.98 W. Being in a vacuum allows less heater power. Oven temperature is very critical to provide enough cesium in the beam but at the same time not wasting it. A switching power supply runs the oven as well as providing 1.2V at 3.4A to the hot wire ionizer which is 4.08 Watts. It took 10 minutes from a cold start for the cesium oven current to drop from being pegged to its final value. After stabilizing, we connected a 470 Ω across the thermistor from the beam tube to shut off the heater. Here is the beam current versus time in minutes as the oven cooled off. Note that it took 17 minutes for the beam current to drop to half value. Continuous lock was maintained. time beam 0 20 3 18 5 17 8 16 9 15 11 14 14 12 17 11 We then reapplied oven power and watched the beam current increase and oven current decrease. time beam oven 0 16 over 50 3 20 missed 5 22 missed 6 21 15 8 20 15 10 20 14 Finally we applied oven power from a 35 minute cooldown and waited for lock. If the oscillator oven is stable, the cesium oven will achieve lock in only two minutes. There is no need to waste cesium if you do not need the instrument to be locked. time beam status 0 8 unlock 2 10 lock 3 12 lock 4 18 lock πθ°μΩω±√·Γλ WB0KVV _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.